Black/Grey Water Tank Odor Under Kitchen Counter

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AGENT86

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Joined
Jan 21, 2013
Posts
92
Location
WNC @ 3400 ft...Annd loving it
I have a somewhat strange problem. There is a somewhat strong odor under the kitchen counter/sink that I can only smell when I open the cabinet door & it seems to be isolated to the upper portion where the kitchen sink drain pipes are & not the lower area which is separated by wood shelving.

After I open the cabinet door the smell quickly dissipates & I can't locate the source. All the fittings on the drain pipes are tight with no leaks that I can find. What can be causing this issue?
 
Could be a failed air admittance valve.  It will look like one of these.  It just unscrews for replacement.
 
How old is the rig?  If it is the valve I would remove it and see what's keeping the flapper open.  It may be repairable.
 
Look a little more closely!! You should find an anti-siphon valve in the drain line just past the P-trap and it will be high up under there. If it is stuck open it will allow tank smells to enter. It can be unscrewed and simply replaced with parts available at any hardware store usually.

(It's job in life is to prevent the water in the P-trap from being sucked out from any vacuum that may be created while dumping the tank).
 
Stu, I was thinking about that. I thought that the vent pipes would allow air to enter the tanks when dumping. I always thought the air admittance valve was to allow water to enter the piping when dumping a full sink of water.

Ren?  :D :) ;)
 
Could well be Ren?, but should that tank vent to the roof get blocked with a mud daubers nest or something (as mine was).... but then, what do I know? I am not a plumber, and that is only my understanding of it's purpose!!
 
I don't see any type of valve at all. Is the anti-siphon valve inside the pipe in such a way that you wouldn't know it was there unless you KNEW it was there? I ask because the threaded part after the  trap where it screws into the longer length drain before it exits through the wall looks larger & different than a standard type fitting although shows no indication that it's anything other than a threaded fitting. If that makes any sense.

Is there anywhere else I should look? I don't see anything like a valve under the bathroom sink either.  It's a 2006 ROCKWOOD 8314SS
 
Typically, what you should have is a 90 degree elbow coming of you sink drain piping someplace. From that, a short length of pipe (around 6 to 8" long) will go up. On top of that will be a female threaded fitting and the air admittance valve screws into that.  Similar to this: https://www.youtube.com/watch?v=W-YaPn7Y5MY
 
Rene T said:
Typically, what you should have is a 90 degree elbow coming of you sink drain piping someplace. From that, a short length of pipe (around 6 to 8" long) will go up. On top of that will be a female threaded fitting and the air admittance valve screws into that.  Similar to this: https://www.youtube.com/watch?v=W-YaPn7Y5MY
Click to expand...


Nothing like that anywhere under there.
 
A brief bit of research seemed to indicate your model might have roof vent pipes for the plumbing. Is this correct? If so, the wind could be getting forced down the vent somehow and that is how you are getting the smell inside. One person noticed it happened while they were moving (driving). So they got some sort of vent cap that goes on top of the roof vents pipes to help prevent air being forced down the vent pipes.
 
Hammster said:
A brief bit of research seemed to indicate your model might have roof vent pipes for the plumbing. Is this correct? If so, the wind could be getting forced down the vent somehow and that is how you are getting the smell inside. One person noticed it happened while they were moving (driving). So they got some sort of vent cap that goes on top of the roof vents pipes to help prevent air being forced down the vent pipes.
Click to expand...
You mean something like this:  http://www.campingworld.com/shopping/item/cyclone-sewer-vent/31992
 
As far as I know, it's one of three things
1) air admittance valve as Ned mentioned
2) no water in the p-trap
3) a cracked or loose pipe

There really is no other way (I think), unless it's one of those systems without a p-trap, in which case it would be that gizmo in place of #2

My money is on an admittance valve hidden under there some place.....  Mine was loose from the factory.  Found it on our last trip... and I hope that was the only source of my problem
 
AGENT86 said:
Nothing like that anywhere under there.
Click to expand...
Do your pipes go straight down thru the floor or does it go through a wall. If it goes into a wall, is there anyway of seeing the pipes on the other side of that wall like maybe taking out a false wall or a drawer.
 
blw2 said:
There really is no other way, unless it's one of those systems without a p-trap, in which case it would be that gizmo in place of #2
Click to expand...
This is the "gizmo" that Brad is talking about:  http://www.hepvo.com/
 
AGENT86 said:
Nothing like that anywhere under there.
Click to expand...

It may be hidden behind a set of drawers and you won't see it until you pull  a couple of them right out and look inside with a flashlight. (I had pulled my stove for other reasons and discovered it quite by accident hidden behind the drawers!! The drawer compartment was separated from the under sink cabinet by a 'wall' and thus it could not be seen by simply looking under the cabinet itself.)

It will be located as high up as possible under there and will likely be in a T fitting, not an elbow, in the horizontal drain pipe.
 
Rene T said:
You mean something like this:  http://www.campingworld.com/shopping/item/cyclone-sewer-vent/31992
Click to expand...

Rene, I didn't see what type and the person who posted about the problem they had didn't provide info as to what kind they used.
 
Hammster said:
Rene, I didn't see what type and the person who posted about the problem they had didn't provide info as to what kind they used.
Click to expand...

No. blw2 (Brad) mentioned this trap in his post and I just wanted to show what he was talking about. I have no idea what the original poster has.
 
Back in 2010 I bought a 95 coachmen 25 ft TT. Had a smell around the sink area. I found a potato had fallen behind a closed area. But still had a smell from the sink. I undid the drain pipes from the double sink to the trap. Pipes full of grey gunk, cleaned them out, smell gone.
 
Rene T, do you notice the smell only when you are camping with the dump hose hooked up and connected into the sewer of the RV park?
I had a similar problem this spring with our new TT when we were camping with full hook up and I left the gray water dump valves open for unlimited use of the gray water. With the gray water valves open ( we have 2  gray water tanks) I noticed this strangle smell when I opened the kitchen cabinet and the smell quickly dissipated. I also notice when we sat outside I could smell a slight  sewage odder when the wind would blow. Thru trial and error I found if I closed the gray water valves this smell inside and out odder was eliminated and did not reoccur.
Other than this scenario I can only comment that perhaps you are picking up a small very minor propane leak from the stove connection to the right of your cabinet. This can be confirmed by shutting off your propane supply.
Reedg


 
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